The manner of transmitting messages between any two points in a telecommunication network is open systems interconnection (OSI). The open system interconnection basic model is described in International Organization for Standardization standard ISO/IEC 7498-1:1994 (ISO, Geneva, 1997). The OSI model uses a seven-layer network architecture. Layer one, the Physical Layer conveys a bit stream to be transmitted through the network at the electrical and mechanical level. It provides the hardware for sending and receiving data on a carrier.
To reduce the chance of data error, a transmit pipe of a wireless LAN (Local Area Network) protocol generates two encoded data streams from an input data stream. The two encoded streams are interleaved prior to transmission. In a receiver, a de-interleaver restores interleaved data to the original order of the encoded data streams. A currently preferred context for performance of de-interleaving is in accordance with a wireless LAN communication protocol set forth by Institute of Electrical and Electronics Engineers (IEEE) Standard 802.11 a entitled “Standard for Telecommunications and Information Exchange Between Systems LAN/MAN Specific Requirements - Part 11: Wireless Medium Access Control (MAC) and physical layer (PHY) specifications: High Speed Physical Layer in the 5 GHz band” (1999).
Bits are provided to the de-interleaver from a de-mapper. The de-mapper may reach a decision as to the value of each transmitted bit and generates a single “receiver best guess” bit for every transmitted bit. This approach is known as a “hard decision.” Alternatively, a de-mapper may generate several bits, i.e. a metric, for every transmitted bit. These bits represent a probability that a particular transmitted bit was either a “one” or a “zero.” This approach is known as a “soft decision.”
The standard de-interleaver implementation generates the de-interleaved stream by moving data into a new buffer and reordering the metrics according to their correct order while doing so. This prior art practice requires machine complexity and cycle time for each operation performed.
In the IEEE 802.11a standard, two permutations define the mapping of each metric from its location in an input buffer to its location in a de-interleaved stream. The de-interleaver permutations are defined as follows:    J denotes the index to the interleaved input buffer before the first permutation;    I denotes the index after the first permutation; and    K denotes the index in the de-interleaved stream after the second permutation.i=s*floor(j/s)+(j+floor(16*j/NCBPS)) mod s  (1)where j=0, 1, . . . , NCBPS−1 and where s=max (NBPSC/2, 1)k=16*i−(NCBPS−1)*floor(16*i/NCBPS)where i=0, 1, . . . NCBPS−1.NCBPS is number of coded bits per symbol.NBPSC is the number of bits per sub-carrier.